Radio interference

Difference Engine: Phones up in the air

WHICH is worse: not being able to use a mobile phone while on board an aircraft—or being able to do so? Just about the last thing most people want is to be trapped next to someone nattering endlessly into a mobile phone, oblivious of everyone within forced earshot. Rudeness and lack of consideration know no bounds for some folk. And sad to report, as mobile phones have proliferated, such crass behaviour is no longer the isolated exception within an otherwise civil crowd. Were the Federal Communications Commission (FCC) to relax its rule banning the use of mobile phones once an aircraft leaves the ground, there would be fist-fights aplenty above the clouds.

Fortunately for those who value at least peace and quiet when crammed in an airline seat, the FCC is in no hurry to relax its ban. However, regulators are finally thinking of permitting the use, during take off and landing, of other sorts of electronic equipment currently forbidden, except when the plane is in level flight. Understanding why this change is possible illuminates a common misconception about what it is that means mobile phones and aircraft do not mix. For the ban exists not (as the public is often led to believe) because mobiles disrupt an aircraft’s sensitive avionics, but rather to stop them playing havoc with the phone companies' receiving equipment on the ground that is trying to handle their calls.

In theory, any piece of electical equipment might interfere with a plane's GPS navigation equipment, VHF omnidirectional range/locators and instrument-landing system. Even gizmos that are not supposed to, such as audio players and video-game machines, may emit spurious radio-frequency energy. The worst of these "unintentional" transmitters are probably the cables and power supplies that passengers bring on board to charge their laptops and tablets from in-seat power sockets provided nowadays by numerous airlines.

Intentional transmitters, like mobile phones, two-way pagers and walkie-talkies, present a different sort of problem. With these, engineers worry about the so-called "near-far” effect. Even if below permitted levels, any spurious emissions they might produce would occur close to an aircraft’s avionics, compared with the weak signal from a ground-based radio beacon hundreds of kilometres away, or the whispers from a GPS satellite thousands of kilometres up in space. The concern here is that weak, distant signals might be drowned out as a navigation receiver captures a spurious signal that may also be weak but is significantly closer.

There are dozens of anecdotal reports of instruments on the flight-deck being affected by passengers using portable electronic devices, or PEDs as they are known in aviation circles. Unfortunately, duplicating these under controlled conditions has proved nigh-on impossible. Both Airbus and Boeing have bombarded their aircraft with electromagnetic radiation at frequencies and power levels used by mobile phones, only to come away empty handed.

In practice, then, the chance of unintentional transmitters doing any harm is infinitesimal. Indeed, that is just as well, because flight crews have had permission from the FAA to use portable computers called “electronic flight bags” in the cockpit since the early 1990s. Today, they carry iPads and other tablets as replacements for the bulky aircraft operating manuals, flight-crew manuals and navigation charts. These portable electronic devices are in much closer proximity to the aircraft’s avionics than anything passengers are likely to bring aboard, and remain switched on throughout the flight.

On top of that many passengers leave their phones, laptops, tablets and other PEDs turned on during take off and landing, even though they are not actually using them. They may not realise it, but closing the lid of a laptop merely puts it into standby or hibernation mode. Meanwhile, the device’s clock circuit continues to hum away and the Wi-Fi chip carries on hunting for a connection. The same goes for mobile phones and tablets, which are often put into standby mode rather than being switched off properly. The latest tablets and smart phones have an “aeroplane mode”, which at least switches off the device’s various radios.

And that is not to consider the scoff-laws who deliberately leave their phones on after the aircraft doors have shut, so they can send text messages and make calls surreptitiously. A three-month study done in 2003 (published subsequently in the Institute of Electrical and Electronics Engineers’ IEEE Spectrum) found that between one and four covert calls were made on each of the 37 domestic flights the researchers monitored with a hidden spectrum analyser.

A decade later, with practically everyone on board now possessing at least a mobile phone, there are probably dozens of such illicit calls being made on every flight. Yet there has still been no airline incident, let alone an actual accident, caused by a personal gadget being used legally or illegally during a flight. Despite 20 years of testing, the authorities have been unable to demonstrate that mobile phones and other electronic devices can interfere with an aircraft’s navigation and communications gear.

The truth is that the FCC never was concerned about the possibility of electronic interference when, in 1991, it banned the use of mobile phones on board aircraft. All it was really worried about was their impact on cellular networks on the ground. These work on the principle that, at any given moment, a mobile phone is within range of only one or two nearby masts. Each mast uses a set of channels different from those allocated to the masts closest to it, but the same as others further away. In this way, each channel can be used, and reused, to carry calls from multiple users.

Unfortunately, a mobile phone operating in an aircraft flying overhead might be within reach of any number of masts using the same channels. This could not only cause calls to be dropped, but would also confuse the network's software—reducing the mobile system’s overall capacity by blocking the reuse of channels.

There is also the added problem of an airborne phone moving too fast across the sky for the ground-based network to respond. The highest speed a mobile network is expected to cope with is that of an express train—not a passenger jet travelling at just below the speed of sound. A mobile used on an aircraft could traverse a tower too quickly to register with the network. If that happened, it would then bombard multiple towers along its route with repeated attempts to register, causing yet further network confusion.

So there are sound technical reasons why the FCC prohibits the use of mobile phones in the air. But why are laptops, tablets, e-readers, audio players and other PEDs banned during take off and landing? Like aviation authorities elsewhere, the Federal Aviation Administration (FAA) says these cannot be used until the flight crew give permission and the aircraft has climbed to an altitude of at least 3,000 metres.

Why so arbitrary an altitude? The standard explanation is that, above 3,000 metres, there would be enough time and height for the flight crew to diagnose any problem potentially caused by an errant gizmo and make a correction. Close to the ground, during take off and landing, there would be a whole lot less.

That might sound reasonable, save for the fact that all those years of tests—and all those live gadgets in the cockpit—suggest the actual threat is approximately zero. Last March, following numerous demands for the ban to be lifted, the FAA unexpectedly told Nick Bilton of the New York Times that it was going to take a “fresh look” at the use of electronic gadgets on board commercial flights. Mr Bilton has been nagging the FAA to relax its regulations governing electronic devices that demonstrably cause no harm to an aircraft’s instruments. A bigger surprise is that he has now been joined by the FCC itself.

On December 6th the commission’s chairman, Julius Genachowski, wrote to the FAA’s acting administrator, Michael Huerta, urging the airline regulator “to enable greater use of tablets, e-readers and other portable electronic devices during [all phases of] flight.” The FCC agreed to work closely with both the FAA and industry to ensure a successful outcome.

It is not that the FAA has been dragging its feet out of bureaucratic bloody-mindedness. The problem is that the current guidelines require each airline to test every make and model of each gizmo it wants the FAA to approve for use on its flights—and then to do the same for every type of aircraft in its fleet. The airlines have baulked at such a monumental task because of the cost. The FAA is now looking for ways to bring airlines, aircraft manufacturers, electronics makers and other interested parties together to streamline the certification process at least for tablets, e-readers, game machines and a few other popular gadgets.

But do not expect such easing to extend to phones. One reason is that, with the enormous number of makes and models in existence, getting all mobiles approved for use on board aircraft would be prohibitively expensive. Another is that the ground-based interference problem has still to be resolved.

Perhaps it never will be; and maybe that will not matter. The FCC has allocated frequencies in the 450 megahertz and 800 megahertz bands for dedicated air-to-ground services that communicate with widely separated ground stations. Small cellular base-stations, known as pico-cells, are beginning to sprout in aircraft cabins, so passengers can make Skype calls to friends and family on the ground, and download content from the internet while airborne. The Wi-Fi connections to an airborne pico-cell are bounced up to a satellite before being beamed down to the ground using one of the special frequency bands allocated for the job.

The service is no bargain. Virgin Atlantic, which expects to have 20 aircraft offering internet access on its Atlantic routes by the end of this year, is charging $1.60 a minute for calls and 32 cents for text messages. Your correspondent is quietly relieved that the cost alone may deter many users—just as it did with those hard-wired, back-of-the-seat phones.

There are three primary reasons that will not be resolved easily, regardless of the dubious prior claims of interference with avionics gear or harnessing. I was in the Cellular industry in the 90s and later in the Satellite Telecom business designing and installing teleconferencing systems for school campuses, integrating many media. I know how these electronics work.

And it doesn't matter. While the problem of a single handset locking up towers or causing routing computer chasing has abated substantially over the last couple of decades, particularly with national carriers now, instead of local and regionals providing limited roaming (yes, BILLING was a HUGE reason for disallowing airborne use of cellphones), these are the three problems that won't go away:

1. It's bloody Rude. Worse still, the instigators are oblivious, provided it is THEIR critically important call about dinner or walking the dog or hairstyles, as opposed to someone else's frivolous call about dinner, the dog or hairdos. There are quite cars on commuter rails and even subway systems (Metros), and all I can say is "thank our lucky stars!" Clearly, that problem won't evaporate. It will always be rude, obnoxious and anger inducing behavior in close quarters.

2. Ballistics. During take-off, landing or turbulent flight, PEDs can become wonderful projectiles... nice hard, sharp and glassy projectiles that can cause real harm. That's why you don't have a beverage during take-off or landing. That's also why you are belted in, so YOU don't become ballistic. The physics of flight and objects within flying objects are unlikely to change, so this is just common sense safety.

3. Radiation. Jetliners are, for intents and purposes, partially electrically perforated Faraday spaces, shielded from a broad range of electromagnetic energy. Aside from the known exposure to radiation that frequent fliers endure, there would be the problem of use of cell phones in the cabin: little 1/2W transmitters may not seem like much, but in an enclosed space, the energy is being reflected back into the cabin. Additionally, RF is not all equal, and at the near to actual microwave frequencies involved with cellphones, there is evidence that there is more than anecdotal risk to living tissue. Multiply this by several to many phones and there could be tens of watts of digital (highly unnatural) RF bouncing about at frequencies that are potentially very dangerous for hours in an "RF Enclosed" space, presenting an unreasonable health risk, if not to the passengers, then to the crew, who fly several timed daily and repeatedly for years compared to non-airline personnel. This may be impossible to fix, as a workplace problem, and may trump all other concerns and carry the day. Compared to the tiny amount of RF involved with BT or Wifi, Cell phone radios emit quite a substantial bit more energy.

In flight use of cell phones, except on Wifi Only radios, is not likely any time soon. Since smartphones nearly all are now capable of calling on Wifi, that will likely be permitted because of the tiny power levels involved. I'm surprised that cellular damping devices haven't been installed in jetliners as they have been in some theaters. They aren't expensive and they work quite well and force the solution upon selfish scofflaws and self-privileged spoiled users.

This article missed the most important reason why cell phones should not be allowed on planes. A recent Israeli study showed that when just 1/4th of the passengers on a train used their cell phones, the levels of microwave radiation exposure exceeded the regulated safe limit. The World Health Organization has classified cell phone radiation as a possible carcinogen, placing it in the same risk category as lead and DDT.

In spite of the level of concern expressed by many independent scientists, the FCC has not performed tests to ensure that wireless use on trains, planes and public buses does not overexpose passengers to dangerous levels of microwave radiation. And, what about the exposure received by children whose smaller skulls and developing nervous systems are most vulnerable to the suspected health risks?

Genachowski, the chair of the governmental agency mandated to protect the public from the exposure to microwave emitting devices, should NOT be recklessly advocating on behalf of the telecom industry. He should instead be calling for more research to determine the actual levels of exposure we all receive from cell phone use on planes, trains and buses. Especially from those situations that simultaneously expose all passengers to WIFI, whether they are aware, or not.

Glad to see that safety means not having a phone in your hand or an ipad on your lap. Quite right.

But in that case, why is it ok to have, say, a book or a hard copy of The Economist in your hand (and at similar risk of becoming and unguided missile)? Maybe the regulators should be looking at that too, and the risks of children having unsecured toys in their little mitts...

I hope the FCC will not relent. An overly chatty neighbor is the last thing one needs on an airplane. We already suffer from obese people who spill over into our seats, scruffy people who don't have the decency to dress up right, smelly people whose personal hygeine is questionable at best, etc. An airplane is different from a train or even a bus; passengers are huddled closer together and there is not room even to walk about. The best way to fly is to sleep and a chatty neighbor deprives even that.

If errant flyers cannot be controlled, the best thing governments and cell phone operators could do is to "tune out" any connection from up above.

Most regulators ban the use of transmitting personal electronic devices (T-PEDs), including mobile phones, in flight. The use of other, non-transmitting, personal electronic devices (PEDs) are allowed during non-critical phases of flight (takeoff, climb, approach and landing). There are several flight safety related reasons for this:

- Active radio transmitters, such as mobile phones, and non-transmitting electronics, including virtually all electronic devices, emit electromagnetic radiation which could theoretically interfere with aircraft avionics.
- Some mobile phone systems cause interference on aircraft radios and intercom systems. This can be very irritating to the crew and disrupt communication.
- During critical phases of flight, it is important that the cabin crew are able to communicate with the passengers, provide information and issue safety instructions to them. It is therefore good practice to prohibit the use of PEDs at this point in the flight.

The ground networks that support mobile phones are not designed to handle connections from phones travelling at high speed or at a height where they are able to connect to several different masts simultaneously. The use of mobile phones in flight therefore causes network problems and additional costs for service providers. Although not a flight safety issue, it is a further consideration influencing the ban on use of mobile phones in-flight.

Interpretation and compliance with regulations is left to the aircraft operator. Most interpret "critical phases of flight" as below 10,000 ft or 3,000 m and prohibit use from when the doors are closed.

Passengers need to adjust their attitude when they step on board an aircraft. They need to listen to all announcements and pay attention to the safety content. They should also take the time to review the Safety Features Card. The landing on the Hudson is proof that emergencies can happen with little time to prepare. So where am I going with this? Instead of thinking safety passengers are too busy with their PED's. The very fact that they intentionally continue to operate the transmitting functions displays a total disregard for the rules of the air. The sad part of all of this is that when there is an accident these very same people are the first to start pointing fingers at others. After all, what did we do before the PED while flying? Relaxed and enjoyed the flight!

That is a function of whether you were raised with manners... or not. It has been impolite to carry on a telephone conversation with others about, or especially in the midst of others for, oh, a century? This novel concept seems to evade people under 30, although they also eschew actual vocal intercourse, instead using text messaging which, in this context, is considerably more polite.

My parents were near complete cultural opposites: one a first generation American born in da Bronx, the other a longline Anglo-Germanic WASP ten or so generations in, raised in the genteel South on horseback on a plantation. They were both adamant that telephone conversations were not radio broadcasts, nor were they to be taken and engaged in within earshot of others even in most impersonal conversations. It is simply not done.

Just because my telephone is in my pocket now (I gave up a hardwired landline in 1997, iirc, very early) doesn't mean I do not still use the thing with the same polite decorum I always have done, and I expect the same of others to comport themselves in the use of their phones as we were brought up to do.

I truly do not want to hear about how much fun last night's tryst was, or what the kids are having for lunch or what the details of the carcrash repair estimate is or your oncologist's obvious attempts to stop your escalating sobbing in public upon learning of your husband's illness, or what kind of lingerie you bought in Milan or who you bumped into at Rio in Las Vegas.

That is crap you shouldn't and WOULDN'T talk about publicly and so trivially in your office amidst your coworkers, and so, just because folks are strangers and "what the hell, who cares... eff-em, they don't know me" is NOT a justification for being obnoxious in what is already a tiring or stressful situation for many flyers.

I've said it elsewhere: the airline companies should have cell radio dampers as some theaters do in all their jetliners. Most people just want to have some peace and quiet, and it is NOT up to others to take measures against the rudest people who are oblivious to life outside their selfish wee sphere of personal space.

Also, if people are traveling together and want to talk with each other, THAT is perfectly natural and generally wanes in short order anyway. At least that's what I've noted on hundreds of flights.

Kids are kids. They are usually reasonably well behaved, but babies are babies. You can't suffocate them, so you do what you did with your own babies: you put up with it. Most fall asleep.

The difference, too, is that they don't know better. The adults do, and they should not even be an issue, yet they are.

If you are anti-social and cannot accept any interfacing whatsoever with others, no matter how tangential, then headphones are perfect for you. Put on a sleep blinder and you're good to go. My choice in those cases, particularly the very few times I've been seated aft of the wing (very rare) has been foam earplugs: they work a champ, are brightly colored so everyone see them when you point at them and you get left alone. The relative silence is nice on some older planes with a lot of air/skin noise.

There is no need to bend over backwards to accommodate people being rude, though.

you said cellphones cause risk to living tissues. I guess you haven't come across Photo-electric effect principle, that if an energy quanta E = hv is smaller than the threshold to knock an electron off, then no matter how high an intensity the waves/energy are, electrons will NOT be knocked off !! Period. The cell phone uses a few GHz of frequency... the energy per microwave quanta is E = h x 2-3 GHz, while visible light red is of ~ 700 THz ! .. Yes, visible light quanta has energy which is 1000 times higher than those in cell phones or microwave ovens! !... we are exposed to visible light all the time 24x7 and suffer no harm... so if electrons orbitting the atoms building the tissues and cells of our bodies suffer absolutely no harm with 700 THz energy quanta, do you think energy quanta of 2 or 3 GHz will damage the tissues ? ... I thought you said you worked in electronics industry for many years !!

The simple approach to limiting cell phone power is to put a microcell station in the plane, with which the phones can communicate. The phones automatically adjust their power, so they'll be running at absolute minimum.

The microcell can:
- Be linked for voice and data via satellite
- Be linked for data, but refuse voice calls
- Be unlinked, and merely serve to keep radio power to minimum.

A recent observation shows all this is rubbish anyway re the use of 'PEDs'
I regulary fly on SingAir, who, like most carriers, forbid use of electronics during take off and landing and they do not turn on the in-flight entertainment until the seat belt signs first go off, and turn them off far too early before descent.
However, I have recently travelled a few times on Qatar Air, their policy is different, just slightly, namely there appears to be none. I have taken off and landed with headphones on watching the in-chair system, or reading my ipad. This is not just a case of different rules in Doha, this is also using Changi, so it is getting really bizaar.

You would think that the integrity of navigation and control systems should be of foremost concern to the people using them on a daily basis: Surely, airline pilots would be careful to avoid using their cell phones in flight?
So, how come then that in a well-publicised near-miss a Jetstar flight on approach to Singapore Changi airport came almost to grief because the co-pilot was distracted by - guess what: Texting on his mobile phone!
It seems that indeed the human factor should be of concern, both in the cockpit and with your seat neighbour, much more so than some far-fetched potential for technical interference.

I didn't say that. Do you truly believe I'm implying that radiation piles up on the floor like glowing dustbunnies or something of that nature? Please. The effect of multiple transmitters is ADDITIVE and the effects on tissues would be CUMULATIVE but we aren't talking about alpha particles lying about on the floor of the cabin or getting lodged in peoples' clothing. I didn't say that, imply it or otherwise allude to that. And it is possible to define a perfect box in which photons stay "forever." But it won't be made of cardboard. What I described bears no relationship whatsoever to your analogy. False equivalency, I'm afraid.

This is not my arbitrary decision: it is a social norm among polite people. Like many traditional social protocols, there may be a core precedent, which is really not important since the underlying cause of a custom of etiquette doesn't alter its practice.

While I don't generally have much patience for inane conversation even if I can follow both sides of the prattle, there is likely the neurological processing drain involved with attempting to synthesize the unheard half of a conversation to resolve the whole of it that makes cell calls so difficult to ignore. Perhaps for the same reason that fight-or-flight reactions are so highly exaggerated in people today to stimuli which are not life-threatening, the interminable urge to resolve the nature of nearby activities before being able to dismiss them may be a bit of a programming error in our species, a price we pay for elaborate language skills compared to other species.

I have found that when flying, I am usually engaged in an activity involving higher language skills: writing, non-leisure reading or, for leisure, high-difficulty crossword puzzles. Unfortunately, in this setting, that I have hearing acuity and bandwidth beyond previously tested limits for people less than half my age ("lucky," I suppose) is perhaps amplifying the problem, but the ability to dismiss a "half-conversation" is difficult, especially when in the middle of another language-based activity.

In fact, it's difficult when you are speaking with someone face to face and someone next to you is on a cell conversation, as may happen on the commuter rail or in a hotel lobby... or worse, your family get together in the living room or on the patio or deck.

The phenomenon reminds me most closely of the smoker's "victimization" at being unable to disrupt and disgust those around them, and that the smoke does not just "stop" when approaching someone who does not like it or gets ill due to it, and neither does the sound of one half of a cell call.

For the same reason that it's inappropriate in a theater, it's inappropriate nearly anywhere else: people are attempting to focus their attention elsewhere.

Therefor, no matter how you cut it, cell or hardwired, taking phone calls seems to be rude with others around for good reason. It is actually logical and practical.

As far as the sleep blinders, didn't I suggest that for those who are truly repulsed by even the sight of social interaction? I think I did.

People are increasingly selfish and rude, in part because of the technology they have desensitizing them to the realities of social interaction... and they those folks have had kids who are young adults now. Handheld cellphones are nearly 30 years in now... and have ALWAYS been associated with rude behavior. It is only natural that the kids of these first-generation adopters would largely be even worse offenders and oblivious to being such.

it has been polite for two people to carry on a conversation in the midst of strangers for much longer than a century. Now, you arbitrarily decide if one of conversents is not present, it is impolite. Why? Because you are missing half of the conversation? It is an interesting question about the psychology of your fairly common reaction. In talking to a psychologist, he speculates that hearing only half of a conversation is distracting and makes the listeners anxious.

Your "antisocial" solution to external noise sources has a cost advantage over mine, it seems an ideal response to the challenge of being comfortable in a large crowd of strangers in a noisy environment. I suggest adding the sleep binders, and eliminate even the sight of a cell phone user, thus completely eliminating anxieties they create in you.

First of all. Having the possibility of using the cellphone promotes talking, and I think its obvious. So it adds to the problem, never the other way arround. But anyway, the most important thing for me here is that flying can continue to be a moment to be disconneted from the online life. Conversations between people will always happen, children will always behave as children. Those are natural things. The use of cellphones are making people "addict" to it, and its a choice. Its like we cant be disconnected any more. As I said. Lets make flying a moment to rest from technology. There is no need to be connected all times. A lot of people use airlines to travel on vacation and those who doesnt can wait to make a phonecall, nothing will happen to them.

Meanwhile, to be consistent, let's force children to be quiet and seat neighbors from carrying on extended conversations. It was never obvious to me why some find it more objectionable for another to carry on a conversation with somebody who you can't hear vs somebody who you can hear. Is it more impolite if you can only listen to half the conversation?

Unfamiliar with RF or sun-burns, Ljiamla? What about radiative heat and cooking, or the damage a fraction of a watt of light or microwaves can do from a maser or laser? I'll let you catch that up for yourself if you need to do.

This is about EMR Watts and the nature of modulation, not just eVs, and certainly not ionization or quantum shell jumping. It's about waves and micropower EMR exposure at 1-2GHz, seen as problematic, in decades of epidemiological data related to cell phones (~0.5W) and towers (usually ~35W), thanks again to Northern European studies.

Burned fast or slow, with a little energy or a lot, with light or microwaves, you're still cooked. Life developed under mostly micro- to milli-watt flux densities other than visible light, save for intermittent transient broadband high energy events like lightning. Visible sunlight is band-passed through the atmosphere, the rest absorbed, or it's deflected by the magnetosphere, which we see working hard in the auroras.

You state, essentially, that if it can't kill you now, it's not harmful. I'm sure you don't feed your baby from leaded glass bottles with BPA laden liners and radium paint markings for night visibility. She would survive that nightly, through much or all of childhood, but...

Digital isn't "natural." Please name natural digital EMR sources. I'll spot you Pulsars, which appear to be pulsed (and coherent) "digital" sources only due to OUR perspective of their rotation, not their actual nature. They're the long cited sole natural mimic of a digital EMR source.

Life evolved with intermittent exposure to modest and specific EMR: visible light. The rest is or can be harmful in varying degrees, just as light is, but at sometimes very low doses.

The unnatural modulations we increasingly apply to synthetic EMR don't seem to help, with known effects upon creatures which rely on EM to function, like birds. This even affects EMR/EMField sensory organs in marine animals like sharks and rays.

Back in Uni, I learned that a Watt is a Watt is a Watt, regardless how you factor voltage against amperage. Has that changed? Still, some Watts are more harmful than others.

So, to your argument (most of that was for non-scientechticians reading this)...

Full sunlight strikes earth at an ideal density of nearly 100 Watts per square foot. That's under 0.7W per square inch of sunburn power. And it's enough to power everything ever. It's stored in the ocean, in oil, in gas (and thus petrol), coal, in food and much more. Gee, turns out to be a LOT of energy.

The legal maximum effective radiated power of handheld cellphones is 0.6W, and we now agree that a Watt is a Watt. MANY phones exceed this maximum RF ERP, even if they are compliant at the "input" to aerial point.

Sunlight also falls away from the equator, weather, etc, so it has a lower power density for most humans, so we can average it to a generous 0.5Wpsi, and can easily do that for cellphones, at 0.5Wpsi, to step the power down.

Now, which is more dangerous: the 700THz waves that reflect off your clothes and flesh or the 2GHz waves that penetrate into your flesh a cm or so and increase brownian motion to heat your flesh via molecular vibratory friction with much greater efficiency than radiative (IR) does? Or, hey, the scarcer much higher Voltage photons at 700T or the plentiful lower voltage photons at 2G? Well, it turns out they're both bad.

Both cause cancer from aggregate dosing: light, cancers of the skin, and cellphone microwaves, sadly, appear demonstrably responsible for temporal brain tumors, at least, for those who used older analog gear. Conversion to DSS multiband phones may be good, may be bad. Time will tell on human lab rats.

But, since part of my education is in neurology and neuropsych, in addition to EE and Biomed, I'll take the cautious route and use ultra-low powered BT headsets and keep the phone away from vital organs. And yeah, I consider the brain vital for most people.

If only people looked at the big picture and had more than one fact to wield. Imagine if government operated on that premise. A guy can dream.

The best compromise is to allow texting only, using Apps like Line2 which can send and receive SMS texts over the airplane's WiFi network and revert to cellular when you are back on the ground. That way we can keep things quiet on board, but still allow communications of logistical info like if the flight is late or asking a friend where they want to meet for dinner after you land.